In order to prevent makeup deterioration with sweat, powders to be mixed into makeup cosmetic compositions such as foundation, eye shadow and mascara are required to have water repellency against sweat. In addition, in order to defend from ultraviolet rays, finely powdery zinc oxide, titanium dioxide, cerium oxide or iron oxide is incorporated as ultraviolet control agents into sun care products. Meanwhile, in order to give water repellency and water proof and improve usability and adhesion to skin as sun screen cosmetics, a powder surface-treated with a silicone compound, a fatty acid, an amino acid or the like are mixed thereinto.
Conventionally, there have been a number of publicly known methods regarding water-repellency treatments of hydrophilic powders to be used in cosmetics, and particularly, utilization of water repellency of silicone compounds has been already well known. For example, disclosure is made of a method in which after a mineral powder such as talc or the like is simply adhered with a silicone compound having hydrogen atoms to directly bond with the powder by mixing in a mixer, the water repellency is given to the mixture by baking under heating; and a method in which silicone treatment is effected by using a silane coupling agent such as dimethyl polysiloxy silazane, trialkoxy polydimethyl siloxane or the like (Patent documents 1, 2, 3).
In addition, recently, many makeup cosmetics such as foundations in which much powders are mixed, stick to slipping property and usability when coated or sprayed on the skins. As compared with conventional products, speadability, slipping property, and adhesionability are improved with lighter touch, and there are observed many cosmetics which are felt comfortable when putting on makeup. Usability and skin adhesion are in a trade-off relationship, and there are not cosmetics which satisfy both of these properties. The powders aiming at the improvement of the slipping property and the usability include spherical ones such as silica beads, alumina beads, nylon powder, PMMA, polyurethane, silicone rubber powder, silicone resin-coated silicone powder, silicone elastomer powder and the like; ones having flattened particle shapes such as hexagonal-crystalline boron nitride, lauroyl lysine, sheet-like barium sulfate, cleavable talc, mica synthesized by wet crushing, sheet-like PMMA, sheet-like cellulose and the like have been developed. Even if these powders are subjected to the above publicly known surface treatment, usability and adhesion to skin are not both improved to satisfactory levels. Besides the powders, other touch improvers include partially crosslinked organopolysiloxanes, represented by KSG-15 (manufactured by Shin-Etsu Chemical Co., Ltd.) in which dimethicone having an Si—H group and vinyl dimethicone are subjected to an addition reaction (Patent Documents 4, 5 and 6). They are in the form of a silicone gel or a silicone elastomer, and are compositions which exhibit the gel property by mixing them with a low-viscosity silicone oil or a low-molecular oil. As the surface-treated powders, soft-touch powders in which surfaces of a scale-like inorganic particles having good adhesion to skin are coated with a resin, and a powder coated with a silicone elastomer to obtain usability with good slip property of the silicone elastomer are disclosed (Patent documents 7, 8, 9 and 10). Silicone elastomer-coated powder having insufficient water repellency is not only obtained, but also many untreated portions of the surfaces of the powder particles are formed on surfaces of powder particles, because the powder has strong agglomeration and they are agglomerated when the powder particles are coated. As a result, such a coated powder has unfavorably undesirable usability and deteriorated adhesion to skin.
As mentioned above, surface-treated powders having good water repellency, smooth and light touch and moist feeling with excellent skin adherability are unavailable, cosmetics having these techniques combined together were yet satisfactory. Moreover, a powder surface-treated with a silicone gel has not been concretely exemplified.